using System;
using System.ComponentModel;
using System.IO;
using System.Runtime.InteropServices;
using System.Text;

namespace Needle.Engine.Utils
{
	internal static class PathUtilsWindows
	{
		// https://stackoverflow.com/a/33487494
		
		private static readonly IntPtr INVALID_HANDLE_VALUE = new IntPtr(-1);

		private const uint FILE_READ_EA = 0x0008;
		private const uint FILE_FLAG_BACKUP_SEMANTICS = 0x2000000;

		[DllImport("Kernel32.dll", SetLastError = true, CharSet = CharSet.Auto)]
		static extern uint GetFinalPathNameByHandle(IntPtr hFile,
			[MarshalAs(UnmanagedType.LPTStr)] StringBuilder lpszFilePath,
			uint cchFilePath,
			uint dwFlags);

		[DllImport("kernel32.dll", SetLastError = true)]
		[return: MarshalAs(UnmanagedType.Bool)]
		static extern bool CloseHandle(IntPtr hObject);

		[DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]
		public static extern IntPtr CreateFile(
			[MarshalAs(UnmanagedType.LPTStr)] string filename,
			[MarshalAs(UnmanagedType.U4)] uint access,
			[MarshalAs(UnmanagedType.U4)] FileShare share,
			IntPtr securityAttributes, // optional SECURITY_ATTRIBUTES struct or IntPtr.Zero
			[MarshalAs(UnmanagedType.U4)] FileMode creationDisposition,
			[MarshalAs(UnmanagedType.U4)] uint flagsAndAttributes,
			IntPtr templateFile);

		public static string GetFinalPathName(string path)
		{
			var h = CreateFile(path,
				FILE_READ_EA,
				FileShare.ReadWrite | FileShare.Delete,
				IntPtr.Zero,
				FileMode.Open,
				FILE_FLAG_BACKUP_SEMANTICS,
				IntPtr.Zero);
			if (h == INVALID_HANDLE_VALUE)
				throw new Win32Exception();

			try
			{
				var sb = new StringBuilder(1024);
				var res = GetFinalPathNameByHandle(h, sb, 1024, 0);
				if (res == 0)
					throw new Win32Exception();

				return sb.ToString();
			}
			finally
			{
				CloseHandle(h);
			}
		}
	}
}